The present invention relates to a method of preparing a flying or permanent splice between a first and second sheet material, to the splices thus obtained and to splicing tapes suitable for splicing a leading edge portion of the outer turn of a roll of sheet material to another sheet material.
Splicing tapes can be used for preparing a joint between two sheet materials such as, for example, between the leading edge portion of the outer turn of a roll of sheet material and another sheet material. The splicing operation can be performed in a static or a dynamic mode.
In the static mode the first and second sheet material may be positioned first in the desired configuration relative to each other, and one or more splicing tapes are then applied in order to join the two sheets together. It is also possible to apply the splicing tape or tapes to one of the sheet materials first. Then the second sheet material is provided, positioned in the desired configuration and the two sheet materials are joined. Splices which are obtained in a static mode of preparation are often referred to as permanent splices. Depending on the configuration of the two sheet materials relative to each other, it can be differentiated between butt splices, overlap splices and staggered overlap splices, respectively. The different configurations are shown and explained in WO 95/29,115.
It is often desirable, however, to prepare splices in a dynamic mode. This allows, for example, in the printing industry, to join the leading edge of the new roll of paper sheet material to the trailing edge of the old, depleting roll of paper sheet material without requiring interruption of the continuous production process. Splices which are obtained in a dynamic mode of operation, are usually referred to as flying splices. A conventional way of making a flying splice tape uses destructible nose tabs as is described in WO 95/29,115. In a first step the new roll is appropriately prepared or xe2x80x9cdressedxe2x80x9d for splicing, as is shown in FIG. 1a which was taken from WO 95/29,115. The leading edge 35 of the outermost turn 32 of the new roll of sheet material 30 is cut, for example, in the form of a W or V or in another appropriate shape. A double-sided adhesive tape 24 is applied to the leading edge portion of the outermost turn 32 which is releasably adhered to the next-to-the-outer turn 31 by the nose tabs 23. The new roll of sheet material 30 is then accelerated to the same speed as the running web sheet of the previous, depleting roll. The running web sheet is then pressed against the new roll 30 and pasted to the double-sided adhesive tape 24 on the outermost turn 32 of the new roll 30. The previous roll is typically cut off from the running web sheet. The nose tab is then subjected to the tractive force exerted by the running web sheet. The nose tab breaks thereby releasing the temporary joint between the outer turn 32 and the next-to-the-outer turn 31 of the new roll of sheet material 30.
An alternative configuration for applying a flying splice which is used in the state-of-the-art is shown in FIG. 1b which was adapted from WO 95/29,115.
A nose tab which is suitable for preparing a flying splice is described in GB 2,294,235. As can be seen from this reference, the nose tab comprises two adhesive layers which are adhered to the under-surface of the leading edge portion of the outer turn and the upper-surface of the next-to-outer turn, respectively. The nose tab furthermore comprises two thin paper layers which are attached to two adhesive layers and embrace a silicon lacquer layer. The new roll of sheet material is then furthermore prepared by applying a double-sided adhesive tape to the leading edge of the outer turn to provide a configuration similar to that of FIGS. 1a or 1b, respectively. When making the splice, the paper web sheet from the depleting roll which is advanced, is adhered to the exposed part of the adhesive layer and the exposed adhesive layer of the double-sided tape, thereby causing the lacquer layer to cohesively split into two parts. On breaking the nose tab of GB 2,294,235 leaves behind two non-tacky surfaces.
Both permanent and flying splices should provide a flexible, strong connection between the two sheet materials or webs and should maintain substantially all of the properties of the sheet material; for example, if the sheet material is paper which can be printed or coated, the splice is preferably thin, flexible, printable, coatable and also repulpable. When using configurations like those of FIGS. 1a and 1b for preparing a flying splice, it is important that air cannot enter beneath the leading edge 35 of the outer turn 32 which would result in the roll unwinding itself at very high speeds thus interrupting the continuous production. In order to prevent air entering beneath the leading edge 35 of the outer turn 32, small destructible adhesive tabs 26 are sometimes applied not only at the noses of the leading edge 35 but, for example, also along the diagonal edges of the leading edge 35 in FIG. 1a or over the lateral edges of the leading portion 34 of the outer turn 32 to the sides of the roll 30 (see FIG. 1b). Configurations like those of FIGS. 1a and 1b are time consuming to apply and require the application of double-sided adhesive tapes and destructible nose tabs.
Another flying splice multi-layer film or multi-layer adhesive, respectively, is disclosed in German utility model DE 92 01 286.8 U1 comprising perforated and non-perforated embodiments. The non-perforated embodiments are required to exhibit a low adhesive force so that the new paper web is easily released after splicing. It is furthermore required that the open adhesive spots which are exposed upon splicing are specifically modified so that they do not stick to rolls, cylinders, rods and spindles. It is disclosed that these requirements can be fulfilled by specifically selecting pressure-sensitive adhesives, permanent adhesives and surfaces, which stick to each other but not to other surfaces such as rolls, spindles and cylinders.
It was therefore an object of the present invention to provide a splicing tape and a method of preparing a flying splice which does not require using a destructible nose tab in combination with a double-sided adhesive tape. It was another object of the present invention to provide a splicing tape which allows to reliably and easily prepare a new roll of sheet material 30 for making a splice and, in particular, for making a flying splice which on delamination leaves behind two non-tacky surfaces. It was another object of the present invention to provide a splicing tape with the peeling force required to delaminate the splicing tape being adjustable within wide limits. Other objects of the present invention can be taken from the following description of the invention.
The present invention refers to a method of splicing a leading edge portion of the outer turn of a roll of sheet material to a further sheet comprising the steps of
(i) providing a splicing tape comprising a carrier layer having on a first major surface a first adhesive layer and on a second major surface opposite to the first major surface in the order given an adhesion-controlling layer, a non-tacky polymer layer and a second adhesive layer, the splicing tape being capable of delamination between the carrier layer and the adhesion-controlling layer or between the non-tacky polymer layer and the adhesion-controlling layer, respectively, when preparing the splice,
(ii) positioning said tape on and adhering it by means of one of the adhesive layers, to the portion of the upper surface of the next-to-the-outer turn of the roll of sheet material facing the leading edge portion of the outer turn so that the other adhesive layer of the splice tape can be fully or partly adhered to the under-surface of the leading edge portion of the outer turn,
(ii) adhering the other adhesive layer of the splice tape fully or partly to the under-surface of the leading edge portion of the outer turn of the roll of sheet material,
(iv) optionally providing an adhesive tape having a first adhesive surface and a second adhesive surface, and adhering one of the adhesive surfaces to the upper surface of the leading edge portion of the outer turn of the roll of sheet material,
(v) adhering the further sheet to the optionally partially exposed surface of the other adhesive surface of the splicing tape and/or to the exposed surface of the other adhesive layer of said optional adhesive tape, and
(vi) separating the further sheet and the outer turn of the roll spliced to it, from the next-to-the-outer turn of the roll thereby effecting delamination between the carrier layer and the non-tacky polymer layer of the splicing tape.
The present invention furthermore refers to a splicing tape suitable for splicing a leading edge portion of the outer turn of a roll of sheet material to another sheet material, said splicing tape comprising a carrier layer having on a first major surface a first adhesive layer and on a second major surface opposite to the first major surface in the order given an adhesion-controlling layer, a non-tacky polymer layer and a second adhesive layer, the splicing tape being capable of delamination between the carrier layer and the adhesion-controlling layer or between the non-tacky polymer layer and the adhesion-controlling layer, respectively, when preparing the splice.
The present invention furthermore refers to a flying or permanent splice between a first and a second sheet material which is obtainable by using splicing tape according to the present invention.